The invention disclosed herein relates generally to postage scales adapted to weigh an article and determine the appropriate postage to be applied thereto. More particularly, the present invention relates to an interface which establishes communication between incompatible systems. Specifically, the present invention is directed to a single cable interface, which enables a plurality of incompatible peripheral devices to communicate with an associated postage scale system processor.
Various postal systems for automatically determining proper postage and interfacing with mailing system peripherals are well known in the art. One such system is disclosed in U.S. Pat. No. 4,395,756 issued to Edward P. Daniels, on Jul. 26, 1983, which describes a microprocessor based system with: a keyboard and display; a scale subsystem processor forming part of a weighing cell, for providing weight information in digital form to the system processor; and, a plurality of peripheral postal devices interfaced to the postal system processor. Another similar system is disclosed in U.S. Pat. No. 4,603,400 issued to Edward P. Daniels on Jul. 29, 1986, disclosing a microprocessor based system with: a keyboard and display; a scale weighing device operatively connected to the system processor; and, postage printing subsystem and peripheral subsystem processors connected to the system processor through a serial communications interface.
The above systems are fully integrated systems and designed to interface with compatible machines. The fully integrated systems are not capable of functioning separately nor are they interchangeable with other peripheral systems.
With increased interest in creating solutions for specific mailing systems to meet individual customer requests, a need to interface postal scale mailing systems with a variety of mailing system peripherals has developed. In many instances, these systems operate under different protocols and thus, are incompatible. One solution to this problem is disclosed in U.S. Pat. No. 4,642,791 issued to Mallozzi et al., on Feb. 10, 1987. This patent discloses an interface that provides communication between a weighing cell providing weight information in the form of code digits representative of arbitrary weight units and optically coupled interface adapter ports which have separate input and output lines.
Another such system is disclosed in U.S. Pat. No. 4,301,507 issued to John H. Soderberg on Nov. 17, 1981, disclosing a serial communications port and a plurality of external devices in which the communications procedure disclosed relates to serial transmission of data and bit by bit return of such data to the transmitter verification. A daisy chain is operatively connected between a plurality of external devices and an associated control is described. However, a communications buffer comprising a daisy chain undesirably prolongs the period of time for transmission of data and increases the possibility of a transmission error.
Yet another such solution is described in U.S. Pat. No. 4,410,961 issued to Dlugos et al., on Oct. 18, 1983 which discloses an interface adapted to interconnect the system processor with a plurality of mailing system peripheral devices. The interface includes a peripheral microcomputer which receives data and command signals from the processor of a scale which communicates through an Echoplex protocol. A multiplexer interconnects the peripheral transmit line of the microcomputer with a selected peripheral device, while an additional multiplexer interconnects the peripheral receive line of the microcomputer with the selected peripheral device. However, only communication between an Echoplex scale and either Echoplex or RS232 peripheral devices is disclosed. A significant disadvantage with this system is that this system requires the user to predetermine and preselect what communication subroutines are necessary to be implemented in order to achieve successful communication. However, with the introduction of a scale which communicates through PB232 protocol a need arose to convert the PB232 protocol to Echoplex protocol.
Further interest in user customized mailing systems, has prompted greater need for allowing the user to interchange a plurality of systems such that features of one system may be used in combination with features of another system. Achieving proper communication between such systems has also created a need for a device that will facilitate proper protocol switching. One particularly desirable interface would provide for the interconnection and communication between a PB232 protocol scale and mailing system peripherals which communicate in either PB232 or Echoplex protocols. Multi-cable interfaces as described in the prior art are difficult to install, asthetically unappealing, and costly.
Based upon the foregoing reasons, it will be appreciated that it is an object of the present invention to provide a single communications interface between a postage value determining system processor and a plurality of peripheral devices associated with a mailing system which is not subject to the disadvantages of the prior art.
Another object of the present invention, is to provide a single interface between a postage value determining system processor and a plurality of peripheral devices associated with a mailing system which allows the system processor to communicate irrespective of the processor protocol.
Thus, it is an object of this invention to provide an interface between a PB232 scale and mailing system peripherals, which use either PB232 or Echoplex protocols.
It is a further object of this invention to provide an interface that allows a PB232 scale to detect whether it is connected to a PB232 or Echoplex protocol peripheral and can automatically switch between Echoplex and PB232 protocols.
Other objects and advantages of the present invention will be apparent from the detailed description considered in conjunction with the preferred embodiment of the invention illustrated in the drawings, as follows.
The above and other objects of this invention are achieved and the disadvantages of the prior art are overcome by means of an intelligent interface cable assembly (hereinafter IICA) between a postage scale system and a plurality of mailing system peripherals. The present invention includes an interface circuit board, which interconnects a postage value determining system processor with a plurality of peripheral devices associated with a mailing system. An IICA is configured to allow a postage scale mailing system such as a PB232 scale to detect the associated peripheral mailing system protocol. The peripheral protocol may be either PB232 protocol or Echoplex protocol. Once the IICA determines whether the peripheral protocol is Echoplex or PB232, the IICA establishes communication between the PB232 scale and the variety of peripheral devices, by converting the PB232 scale protocol to the protocol of the peripheral device, such as for example, either Echoplex or RS232 protocol.
The IICA is situated between the postage scale system and any one of a plurality of mailing system peripherals. The IICA detects which signal protocol is in present operation. Based upon detecting what signal is received from the peripherals, the IICA then switches to the postage system signal, which corresponds to the signal of the peripheral, thus enabling communication. In typical operation, the postage scale is an RS232 protocol while the mailing system peripherals are either RS232 protocol or Echoplex protocol. RS232 and Echoplex protocols are well known in the art, a detailed description of the individual protocols is not necessary for an understanding of this invention. In general, Ecoplex protocol is serial character asynchronous, bit synchronous, in message form, with the bits of the message being timed in accordance with a given schedule. The messages are returned or echoed by the recipient, bit by bit, for checking. While the PB232 protocol is a variation of the RS232 Protocol, wherein, not all of the available RS232 signals are used, however, voltage levels remain the same.
The IICA includes a circuit board that has both an RS232 to Echoplex converter, and an Echoplex to RS232 converter. The IICA maintains a physical connection at both the scale and the peripheral device through physical ports having multiple pins. The IICA as described in this invention is provided within one cable assembly. However, the IICA may also be included as an internal connection within the postage scale system circuit board or within the circuit board of the mailing system peripherals.
In one operation, the IICA receives a RS232 message on its associated port, detects the peripheral protocol, and then outputs the message to the peripheral device. Conversely, the IICA will also receive Echoplex messages on its associated port, detect the peripheral device copular protocol, convert the input signal to the equivalent Echoplex format, and output the converted signal on the associated Echoplex port.
The IICA also provides trip circuitry to allow scales communicating via PB232, the ability to not only set Echoplex or PB232 protocol, but, also to trip a mailing machine for printing postage. When a set dollar value amount is transmitted to an electronic postage meter, a request for the value set is then transmitted to the meter. The microcomputer awaits receipt of a signal indicating the amount which has been set by the meter; this value is then transmitted to the system processor for comparison with the set value originally transmitted. Upon a trip command, the microcomputer transmits a trip signal to a mailing machine for tripping the meter and awaits receipt of a meter trip complete signal from the postage meter. In the present invention, the mailing machine trip may originate from the IICA or from the peripheral device depending upon whether the IICA detects a PB232 protocol or an Echoplex protocol.
A plurality of communications subroutines are stored in the microcomputer program memory. Thus, versatility in the selection of peripherals which may be employed in conjunction with a stand-alone postage scale is desirable and by present invention available. A system output line is provided for communications with a peripheral device employing either the RS232 or Echoplex communications.
These and other objects and advantages of the present invention will become more apparent from an understanding of the following description of a presently preferred mode of carrying out the invention when considered in conjunction with the accompanying drawings.